Excel Performance Problems

How to Fix Excel Files Opening Slowly After a Microsoft 365 Update

Steve K Sep 30, 2026 869 views

Question details

The user needs to resolve a performance issue where Excel workbooks, particularly those with imported data or defined names, open very slowly following a recent Microsoft 365 update.

How to Fix Excel Files Opening Slowly After a Microsoft 365 Update

Product: Microsoft Excel
Device & OS: Windows
Scenario: Opening existing Excel workbooks containing imported data after installing a recent Office update.
Observed behavior: Excel files experience severe performance drops and load significantly slower than usual due to compatibility bugs introduced by the update.

Before you start

Before making changes to your software, verify your current Microsoft Office version and ensure all your important Excel workbooks are saved and closed.

Solution 1Recommended

Roll Back Microsoft Office to an Earlier Version

Revert to a previous stable build of Office using Command Prompt to immediately resolve update-related performance issues.

If Microsoft is still investigating the issue and has not yet released a patch, rolling back to the previous version is the most effective immediate workaround. You will need administrator privileges to execute this fix.

Close All Office Applications

Ensure Excel, Word, Outlook, and all other Office applications are completely closed.

Open Command Prompt as Administrator

Click the Start menu, type 'cmd', right-click on 'Command Prompt', and select 'Run as administrator'.

Navigate to the Click-to-Run Folder

In the Command Prompt window, type 'cd %programfiles%\Common Files\microsoft shared\ClickToRun' and press Enter.

Execute the Rollback Command

Type the rollback command specifying a valid earlier build number (e.g., 'officec2rclient.exe /update user updatetoversion=16.0.17531.20152') and press Enter to begin the downgrade process.

Roll Back Microsoft Office to an Earlier Version

Pause Automatic Updates: After rolling back, open Excel, go to File > Account > Update Options, and click 'Disable Updates' to prevent Office from automatically reinstalling the problematic update. Remember to re-enable them once Microsoft releases a permanent fix.

Solution 2

Check Update History and Report the Issue

Monitor Microsoft's release notes for a permanent patch and submit feedback directly to the Excel team.

Free Microsoft Office alternative

Try WPS Office for Fast and Reliable Spreadsheet Performance

If recent Microsoft 365 updates are slowing down your workflow and you don't want to deal with complex rollback commands, consider switching to WPS Office. It is a free, lightweight alternative that handles large datasets smoothly and offers full compatibility with your existing Microsoft Excel files.

1. Download and Install WPS Office: Visit the official WPS website, download the free installer, and follow the simple setup instructions.
2. Open Your Spreadsheets: Launch WPS Spreadsheets, click 'Open', and select your existing Excel workbooks to experience fast, uninterrupted loading times.

Free and lightweight with lightning-fast application startup speeds.Seamless compatibility with Microsoft Excel formats (.xlsx, .xls, .csv).Familiar user interface that requires zero learning curve.Stable performance without forced background updates disrupting your work.

microsoft office alternative - wps office

Frequently Asked Questions

Why do my Excel files suddenly open so slowly?

This is often caused by compatibility or performance bugs introduced in a recent Microsoft 365 update, especially if your workbook imports data from multiple files or uses complex defined names.

How can I find the correct version number to roll back to?

You can find valid build numbers by checking the official Microsoft 365 Update History page online. Look for the version number released immediately prior to your current version.

Will rolling back my Office version delete my spreadsheets?

No, rolling back to an earlier Office build only affects the application software. Your personal Excel workbooks, macros, and data will remain safe and completely unchanged.

How long does it usually take for Microsoft to release a fix?

The timeline varies depending on the complexity of the bug. It can range from a few days for critical issues to several weeks for standard patch cycles, which is why rolling back is often recommended for immediate relief.

Excel & Data Problems